Chain



5 0,1944. A. E. FOCKE Re. 22,488

CHAIN Original Filed May 25, 1939 INVENTOR ATTORNEYS.

Reissued May 30, 1944 CHAIN Arthur E. Focke, Indianapolis, Ind.,assignor to Diamond Chain and Manufacturing Company, Indianapolis, Ind.,a corporation of Indiana Original N 0. 2,293,029, dated August 18, 1942,Se-

rial No. 275,715, May 25, 1939.

Application for reissue August 4, 1943, Serial No. 497,317

16 Claims.

My invention relates to chains, especially power-transmission chains,and has for its object the improvement of the wearing qualities and/ orthe strength of such chains.

The design of a chain of the type with which my invention is concernedis usually a compromise between wear-resistance and strength. Certainparts of the chain are subject to both wear and stress; and, in thesteels of which chain elements are commonly formed, strength andwear-resistance are, to an extent, incompatible properties. That is, achain element of a steel selected or treated to obtain maximum strengthwill be relatively susceptible to wear; and, conversely, a, chainelement of a steel selected or treated to obtain maximum wear-resistancewill be relatively weak. I use the term strength herein to denote notonly resistance to steady loads but also resistance to fatigue andshock. Through the practice of my invention, I am enabled to make chainelements possessing the usually incompatible properties of relativelygreat strength and relatively high wear-resistance, and thus I canproduce chain which, for any given strength, will possess greaterwear-resistance or, for any given wear-resistance, greater strength thanprior chains of which I am aware.

In the conventional roller-type chain, which for purposes ofillustration may be taken as an example of common forms of chains towhich my invention is applicable, bushing-links alternate withpin-links, the latter having pins which extend through the bushings ofthe former. As the result of flexing of the chain over its associatedsprockets, wear tends to occur at the interengaging faces of thebushings and pins, such wear being localized over about one-half thecircumference of those interengaging surfaces. At the same time, thepins are also subjected to bending stresses and to shear. In embodying minvention in such a chain I subject the pins, and possibly also thebushings, to a differential treatment which will increasewear-resistance at those surface portions most subject to wear whilestill leaving the remaining surface portions possessed of their normal,or even an enhanced, strength.

The accompanying drawing illustrates my invention: Fig. 1 is a plan of aportion of a rollertype power-transmission chain with portions thereofbroken away; Fig. 2 is a side elevation of the chain with parts thereofbroken away on the section line 2-2 of Fig. 1; Fig. 3 is a plan, inpartial section, or a bushing-type chain; and

Fig. 4 is a fragmental isometric view of a blocktype chain.

The chain shown'in Figs. 1 and 2 is made up of alternating pin-links andbushing-links. Each of the latter comprises a pair of spaced side platesIll having near their end holes for the reception of bushings l I, whileeach of the pin-links comprises a pair of side plates l2 having at theirends holes for the reception of pins 13. The pins [3 of the pin-linkspass through the bushings I l of the bushing-links and so serve to makea continuous chain. Rollers l4 mounted on the bushings II engage theteeth of the driving and driven sprockets (not shown).

In a chain such as that illustrated and described, the tension in thechain is transmitted between each pin l3 and its associated bushing IIat that side of the pin indicated at i6 in the drawing, i. e., that sideof the pin which lies nearest the center of the associated pin-link. Asthe chain passes over the sprockets, the bushings II rotate on theirrespectively associated pins l3; and, as a result of the loadtransmitted between each pin and bushing at the point indicated by thereference numeral l5 and for a distance in opposite directions from thatpoint, a marked tendency to wear occurs.

To resist this wearing tendency it has been proposed to harden thesteel'pins and bushings, or at least the surface portion thereof.However, the hardening process or heat treatment best calculated toincrease Wear-resistance is not the heat treatment which will result inmaximum strength, and vice versa. In fact, with some steels, hardeningto produce maximum wear resistance may make the steel weaker than it wasbefore treatment. As a result, a chain which has such elements as pinsand bushings hardened, either throughout or uniformly over their surfaceportions, to produce maximum wear-resistance will be weaker than itmight otherwise be. Conversely, a chain which has its elements treatedto produce maximum strength will be less wear-resistant than it mightotherwise be.

To make a chain which will possess both satisfactory wear resistance andsatisfactory strength I subject chain elements which must resist bothwear and stress to a differential heattreatment designed to produce orretain satisfactory wear resistance over surface portions sub,- ject towear and to produce or retain satisfactory strength throughout otherportions. De-

pending upon several factors including the size of the chain elementsand the use to which the chain is to be put, the treatment of the chainelements may have for its primary purpose either the increasing ofstrength or the increasing of wear-resistance. If the primary purpose istoincrease strength, the differential heat-treatment results in aretention, or even in an enhancement, of the effective wear-resistance}while if; the primary purposeis to increase wear-'resistance, thedifierential heat treatment results in a retention, or even in anenhancement, Of'..i'

strength.

. In the case of roller chain, it will usually be necessary to subjectonly the-pins to th dii Ter--., ential heat-treatment, although thebushings, may be similarly treated if desired. There are:

several different ways in which thepins (or bushings) may be treated toproduce the desiredfdif} ferential characteristics. For eiiample, if'thepins or bushings are made of mild steel, as they usualtrated in Fig. 3 abushing-type chain in which the bushings themselves directly engage thesprockets without any interposed roller. In such a chain the bushings30, instead of being of uniform diameter throughout their length a inthe chains of Figs: 1 and 2,- have a body diameter which enablesfitliemz-to' co-Qperate 'With the associated sprockets and end portions ofreduced diameter which are received in the side plates In of the bushinglinks. occur most rapidly on that side of the pin indi- In such a chain,Wear tends to cated by. the reference numeral 16, and each pin maybetreated, as previously described, so that it .will be relatively.wear-resistant at that point and relatively strong elsewhere.

'Ihe chain shown in Fig. 4 is of the block type, in'wh'ich'the'pin-links|2I3 are interconnected by blocks 25 having at their ends holes 26through ly are, I may increase the wear-resistance of those portionssubject to wear by case-hardening such portions, confining thecase-hardening to the desired portions b treating the remainingportions, as by copper-plating, to prevent the penetration thereof bycarbon from the carburiz} ing material employed in the case 'hardeningprocess. By this treatment, the p ns or bushings are rendered relativelyhard and wear-resistant over those surface portions where wear is mostlikely to occur,.while the remainder of the thereof as bycase-hardening, and then subject i the pin or bushing to a: differentialtempering process, tempering those portions subject to wear to a pointwhich will produce optimum wear re,- sistance and those portions notsubject to wear to a point where optimum strength andtoug'hness willresult for example, I may subject the. wearing portions to temperingtemperatures; in the neighborhood of 200, while theremaining portionsare subjected to a temperature in the neigh borhood of 500. Suchdifferential heating of the chain elements to obtain differentialtempering may be readily accomplished by knownfmethods of heating, suchas through the use of high-frequency induction, and may be'employe'd notonly to increase wear-resistance over portions subject to wear but also(and concomitantly) to increase the strength of other portions. I I 1 Inassembling the chain, it is essential that the wear-resistant portion ofeach pin or bushing be disposed in proper relation to the associatedside plates. To aid in securing this disposition of the pins orbushings, they may be provided exteriorly with indicia indicatingfwhichside thereof is the harder side. In the drawing, I have shown eachbushing II as provided in one end with a shallow radial groove 20011that side thereof opposite the harder portion, and each pin I3 asprovided with an eccentricrecess 2| near the harder portion thereof. Byassembling the links of the chain with the indicia on the pins and thebushings near the center of the respectively associated links, theharder portions of the pins and bushings will be disposed in properrelationship. That is, the harder portion of each pin will be theportion thereof nearest the center particular roller-type ofpower-transmission chain illustrated in Figs. 1 and 2. 'Thus, I haveilluswhich the pins l3 pass. Here again each pin tends to wear mostrapidly on that side thereof nearest the center of the associated pinlink, and that side-portion of the pin maybe treated as abovedescribed'to obtain desired wear-resistance and strength. If'desir'ed,the blocks may also bedifferen'tially treated.

hatever the type of chain, the treatment of the pins to producedifferential surface char acteristics results in a more satisfactorychain; for the p'ins 'are str'onger'and tougher than if their entiresurface portions were treated topromote wear resistanceand will wearbetter than if they were treated throughout to increase their strengthandtoughness. The bushings, whether of. the roller-type chain "of Figs..1 and 2 or of the bushing-type chain of Fig. 3, may alsobedifferentially treated; but, as pointed out above, the Wearresistanceof a bushing: 15 a more important consideration than is itsstrength. z

Other factors: than wear-resistance and strength may-influence thearrangement of the relatively. hard and relatively strong, portions ofthe chain elements. Thus the rigidity of, an individual chain linkdepends largely upon the fit of. the pins (or bushings.) in theassociated side bars It is customary for the pins to have a press fit inthe sidebars; and in some instances, especially Where the pins possessapproximately the same hardness as theside bars intowhich they ,arepressed, galling occurs as the pins'are pressed into the side bars andthefit consequently becomes less firm than it otherwise might be. Thepossibility of, galling may be reduced if the pin-ends which enter theside bars, or at least the cylindrical surface portions of such pin'ends, are made harderthan the sidebars. "By any of the methods abovedescribed the cyIi'ndricaLI'surface of the pin maybe made,relatively'fhard throughout its circumference. at the ends of'the pinand. over a .portion of itscircumference betweensuchen'dathe remaining.portions of the pin being relatively stronger and softer.

Iclaim as. my inv'ention;

1.,A powertran smission chain, comprising a1- ternating pin links and.bushing-links, each of said bushing-links. comprising two. spaced bushingsandieach of said pin-links comprising two spaced pins passingrespectively through bushingsof adjacent bushing-links, that surfaceportion of each pin nearest the center of the, pinlink being'f harderthan'the remainder of thepin andthe adjacent surface portion of theassociated bushing 'bi'n'g'harderthan the remainder of such 2;jdpowertr'ansmission chain, comprising-a1? te'rnatin'g' pin-links andbushing-links, each or said bushing-links comprising two spaced bushingsand each of said pin-links comprising two spaced pins passingrespectively through bushings of adjacent bushing-links, that innersurface portion of each bushing nearest the adjacent end of thebushing-link being harder than the remainder of the bushing.

3. The invention set forth in claim 2 with the addition that eachbushing is provided exteriorly with indicia indicating which surfaceportion thereof is the harder.

4. The invention set forth in claim 2 with the addition that eachbushing is provided on at least one end surface with indicia indicatingwhich surface portion thereof is the harder.

5. A power-transmission chain, comprising a series of interconnectedlinks, alternate ones of said links being pin-links comprising spacedside plates and unitary pins which pass through said side plates andalso through end portions of the other links, that surface portion ofeach pin nearest the center of the pin link being harder than theremainder of the pin.

6. A power-transmission chain, comprising a series of interconnectedlinks, alternate ones of said links being pin-links comprising spacedside plates and unitary pins which pass through said side plates andalso through end portions of the other links, that surface portion ofeach pin nearest the center of the pin link being more wearresistant andless strong than the remainder of the pin.

'7. The invention set forth in claim 6 with the addition that each pinis provided exteriorly with indicia indicating which surface portionthereof is the harder.

8. The invention set forth in claim 6 with the addition that each pin isprovided on at least one end surface with indicia indicating whichsurface portion thereof is the harder.

9. A power-transmission chain, comprising a series of interconnectedlinks, alternate ones of said links being pin-links comprising side barsand spaced pins whose end portions pass through the side bars and whoseintermediate portions are received in end portions of the other links,the surface portions of the pins at the ends thereof and the surfaceportion of the pin between the side bars and nearest the center of thepin link being harder than the remaining portions of the pin.

10. A chain, comprising a longitudinal series of chain elements andmeans associated with adjacent elements for pivotally interconnectingthem, said means including a transverse pivot pin non-rotatablyassociated with one of each pair of adjacent elements and a bushingwhich rotatably receives said pin and which is nonrotatably associatedwith the other element of such pair, that surface portion of said pinnearest the longitudinal center of its associated element being harderthan the remainder of the pin and the adjacent surface of said bushingbeing harder than the remainder of such bushing.

11. A chain, comprising a longitudinal series of chain elements andmeans associated with adjacent elements for pivotally interconnectingthem, said means including a transverse pivot pin non-rotatablyassociated with one of each pair of adjacent elements and a bushingwhich rotatably receives said pin and which is non-rotatably associatedwith the other element of such pair, that inner surface portion of saidbushing nearest the end of its associated element being harder than theremainder of the bushing.

12. A chain, comprising a longitudinal series of chain elements andmeans associated with adjacent elements for pivotally interconnectingthem, said means including a unitary transverse pivot pin non-rotatablyassociated with one of each pair of adjacent elements and rotatablyreceived in a transverse opening in the other element of such pair, thatsurface portion of said pin nearest the longitudinal center of itsassociated element being harder than the remainder of the pin.

13. In a chain having a series of links each comprising a pair oftransversely spaced side bars, means for pivotally interconnectingadjacent ones of said links, each of said means comprising a pivot pinwhose end portions pass through and are rigid with the side bars of itsassociated link and a bushing rotatably mounted on the intermediateportion of said pin and having its end portions rigidly received in theside bars of its associated link, the surface portions of said pin atthe ends thereof and the surface portion of the pin within the bushingand nearest the center of the associated link being harder than theremaining portions of the pin.

14. In a chain-link, a pair of longitudinally extending, laterallyspaced link-plates provided at corresponding ends with aligned openings,and a unitary pivot pin non-rotatably received in and extending throughsaid openings and adapted between said plates to be rotatably receivedin a transverse opening of another chain-link, that surface portion ofsaid pin between said plates and nearest the longitudinal center of saidplates being harder than the remainder of the pin.

15. In a chain-link, a longitudinally extending link-plate provided nearone end with a transverse opening and a bushing non-rotatably mounted insaid opening and adapted to rotatably receive a transverse pivot-pin ofanother chain-link, that inner surface of said bushing lying nearest theend of said link-plate being harder than the remainder of the bushing.

16. A chain, comprising a longitudinal series of chain elements andmeans associated with adjacent elements for pivotally interconnectingthem, said means including a transverse pivot pin non-rotatablyassociated with one of each pair of adjacent elements and rotatablyreceived in a transverse opening in the other element of such pair, thatsurface portion of said transverse opening nearest the end of itsassociated element being harder than the remainder of the element inwhich it is located.

ARTHUR E. FOCKE.

